الفهرس 
abstractOnly 14 pages are availabe for public view
 |  | from | 194 |  |  |
| | | from | 194 | | |
Abstract
Bronchial asthma is a very common chronic disease in respiratory system in which the constricted airways become inflamed and are lined with excessive amount of mucus (Harold et al., 2008).ِ Asthma prevalence is highest in westernized, industrialized countries (Mosali M, Fabian D et al., 2004) and we have recently proposed that vitamin D deficiency may explain some of this pattern (Litonjua AA et al., 2007) Decrease serum level of vitamin D in children with asthma are associated with increase corticosteroid use (Searing et al., 2010). The main source of vitamin D is de novo synthesis in the skin .Although vitamin D is obtained by food,diatry intake alone is often insufficient and supplying only 20% of body,s requirement (Cutolol and Osta;2008).The best indicator of vitamin D status is the concentration of circulating 25, hydroxyvitamin D (Wharton and Bishop, 2003).Recent discoveries indicate that vitamin D has function, unrelated to calcium, specifically in cell differentiation and in the immune system (Cantorna et al., 2004).